His horse: a horse he owned? and/or had been riding? Was he riding it when he shot it? Was it already dead? Did he intend to shoot it? Did he think he was shooting something else? another horse? Did he need the horse to get somewhere? or to escape from something? and shot himself after realising that this was no longer possible? The horse was incapacitated after he shot it? and this is why it doesn't matter if the shot was lethal? Did he intend to shoot himself? and kill himself?

His horse: a horse he owned? Yes. and/or had been riding? Yes.Was he riding it when he shot it? No.Was it already dead? No.Did he intend to shoot it? Yes.Did he think he was shooting something else? No. another horse? No.Did he need the horse to get somewhere? No, or at least that wasn't on his mind. or to escape from something? No. and shot himself after realising that this was no longer possible? No.The horse was incapacitated after he shot it? Irrel. and this is why it doesn't matter if the shot was lethal? no.Did he intend to shoot himself? Yes.and kill himself? Yes.

Was anyone riding the horse when he shot it? Was it carrying anything? Was it moving? away from him? quickly? Did he know it was his horse? Did the first shot have any other effect besides injuring/killing the horse? If so, is this effect related to the unusual conditions they were in?

Was anyone riding the horse when he shot it? No.Was it carrying anything? YES.Was it moving? away from him? quickly? Irr.Did he know it was his horse? Yes.Did the first shot have any other effect besides injuring/killing the horse? YES.If so, is this effect related to the unusual conditions they were in? Somewhat.

Is the location where this happened relevant? In a desert? In a city? On earth? Did his first bullet also hit something other than the horse? Is this relevant? Were there more people around when this happened? Is anyone else involved in the story (other than him and his horse)?

Did he intend to eat the horse after shooting it? but the bullet hit his bottle of water? and he shot himself rather than die of thirst? Precisely. ***********SPOILER is nicely wrapped up in the above questions. Good job John!